Move DWC2 driver out of staging

The DWC2 driver should now be in good enough shape to move out of
staging. I have stress tested it overnight on RPI running mass
storage and Ethernet transfers in parallel, and for several days
on our proprietary PCI-based platform.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index 70d7c5b..1ae2bf3 100644
--- a/drivers/usb/Makefile
+++ b/drivers/usb/Makefile
@@ -7,6 +7,7 @@
 obj-$(CONFIG_USB)		+= core/
 
 obj-$(CONFIG_USB_DWC3)		+= dwc3/
+obj-$(CONFIG_USB_DWC2)		+= dwc2/
 
 obj-$(CONFIG_USB_MON)		+= mon/